A composition (or an aggregate) comprising an epitaxial h-BN/BNNT structure that comprises a hexagonal boron nitride structure that is epitaxial with respect to a boron nitride nanotube structure. Also, a composition (or an aggregate) that comprises independent boron nitride nanotubes, in which a total mass percentage of independent hexagonal boron nitride and residual boron in the composition is not more than 35%. Also, a composition (or an aggregate) in which not more than 1% of independent boron nitride nanotubes and boron nitride nanotube structures have a dixie cup or bamboo defect. Also, a composition in which at least 50% of independent boron nitride nanotubes and boron nitride nanotube structures are single-wall. Also, a method of making a composition that comprises epitaxial h-BN/BNNT structures.

GaAs IR window slabs having largest dimensions that are greater than 8 inches, and preferably greater than 12 inches, are grown using the Horizontal Gradient Freeze (HGF) method. Heat extraction is simplified by using a shallow horizontal boat that is only slightly deeper than the desired window thickness, thereby enabling growth of large slabs while also minimizing material waste and fabrication cost as compared to slicing and shaping thick plates from large, melt-grown boules. Single crystal seeds can be used to optimize the final orientation of the slabs and minimize secondary nucleation, thereby maximizing yield. A conductive doped GaAs layer can be applied to the IR window slab to provide EMI shielding. The temperature gradient during HGF can be between 1? C./cm and 3? C./cm, and the directional solidification can be at a rate of between 0.25 mm/h and 2.5 mm/h.

A nucleation structure for the epitaxial growth of three-dimensional semiconductor elements, including a substrate including a monocrystalline material forming a growth surface, a plurality of intermediate portions made of an intermediate crystalline material epitaxied from the growth surface and defining an upper intermediate surface, and a plurality of nucleation portions, made of a material including a transition metal forming a nucleation crystalline material, each epitaxied from the upper intermediate surface, and defining a nucleation surface suitable for the epitaxial growth of a three-dimensional semiconductor element.

A semiconductor film includes a two-dimensional (2D) material layer having a hexagonal in-plane lattice structure, and a substantially planar Group IV semiconductor layer having a direct band gap on the 2D material layer. A method of fabricating a semiconductor material includes growing a Group IV semiconductor material on a two-dimensional material having a hexagonal in-plane lattice structure. This growth process results in the Group IV semiconductor material having a direct band gap. The semiconductor films may be used in any optoelectronic device, including flexible devices.

A multi-walled titanium-based nanotube array containing metal or non-metal dopants is formed, in which the dopants are in the form of ions, compounds, clusters and particles located on at least one of a surface, inter-wall space and core of the nanotube. The structure can include multiple dopants, in the form of metal or non-metal ions, compounds, clusters or particles. The dopants can be located on one or more of on the surface of the nanotube, the inter-wall space (interlayer) of the nanotube and the core of the nanotube. The nanotubes may be formed by providing a titanium precursor, converting the titanium precursor into titanium-based layered materials to form titanium-based nanosheets, and transforming the titanium-based nanosheets to multi-walled titanium-based nanotubes.

A composite material includes: an apatite crystal in the form of a tube; and a functional component accommodated in the apatite crystal tube and constituted by a material having physical properties different from those of the apatite crystal. The apatite crystal may be a monocrystal given by the general formula M.sup.2.sub.5(PO.sub.4).sub.3X, where M.sup.2 denotes at least one element selected from the group consisting of divalent alkali earth metals and Eu, and X denotes at least one element or molecule selected from the group consisting of halogens and OH.

A method and apparatus for estimating a concentration of chemicals in a fluid flowing in a fluid passage is disclosed. A sample of the fluid is placed on a substrate comprising a first layer of carbon nanotubes and a second layer of metal nanowires. An energy source radiates the fluid sample with electromagnetic radiation at a selected energy level, and a detector measures an energy level of radiation emitted from the fluid sample in response to the electromagnetic radiation. A processor determines a Raman spectrum of the fluid sample from the energy level of the emitted radiation and estimates the concentration of a selected chemical in the fluid sample based on the Raman spectrum.

A method for making a nanostructured material includes the steps of: providing a mixture of carbon nanoparticles (CNPs) having a selected composition; providing intercalation nanoparticles (INPs) configured to intercalate the carbon nanoparticles (CNPs); intercalating the carbon nanoparticles (CNPs) by mixing the intercalation nanoparticles (INPs) in a selected CNP:HNP ratio to form an intercalated material; and combining the intercalated material in a base material in a selected concentration with the base material providing a matrix for the intercalated material.

A method of preparing a boron nitride material, such as boron nitride (BN) or boron carbonitride (BCN), is provided. The method may include providing a substrate, and sublimating an amine borane complex onto the substrate to obtain the boron nitride material. The amine borane complex may include, but is not limited to, borazine, amino borane, trimethylamine borane and triethylamine borane. In addition, the temperature at which the sublimating is carried out may be varied to control composition of the boron nitride material formed. In addition, various morphologies can be obtained by using the present method, namely films, nanotubes and porous foam.

A floating catalyst chemical vapor deposition system produces nanotubes. The system includes a reaction chamber, a heater for heating a nanotube-material precursor and a catalyst precursor, and an injector for injecting the precursors into the chamber. In the chamber, the catalyst precursor is pyrolysed to produce catalyst particles, and the nanotube-material precursor is pyrolysed in the presence of the catalyst particles in order to produce nanotubes. A controller controls at least one operational parameter, e.g., injection temperatures of the precursors, flow rates of carrier gases of the precursors, and a reaction temperature of the chamber and of the precursors. An injection pipe extends into the chamber to an adjustable extent in order to control the injection temperature of the catalyst precursor and/or the nanotube-material precursor.